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Is a vertical stabiliser needed for straight line flight in a glider?
My team is designing a glider and I am unsure about whether or not to include a vertical stabiliser. The task the glider must complete is to achieve the largest possible displacement in a straight line.
Our glider will not be able to automatically adjust the vertical stabiliser's position so it would stay upright and inline with the glider's fuselage for the duration of the flight. Since our glider does not require any changes in it's yaw angle (because it is flying in a straight line), I don't think there is a need for it.
Should we include a vertical stabiliser or not?

Will your design have another active (control) or passive (stability) means of countering yaw disturbances (e.g. wind, turbulence or minimal asymmetries)? Is the design stable in yaw due geometry even without stabiliser?

As of now we just have symmetrical wings and glider body, so no ways of countering yaw disturbances except for minimal asymmetries. Is it safer to include the static vertical stabiliser to counter the small disturbances in yaw?

I'm assuming this is unmanned.

Yep just a casual project.

Aren't you going to tell us whether the wings are swept or not?  Google "Zagi glider".  Those fly ok even if you take the fins off.  Lots of info missing here.  If the vertical fin fell off a typical sailplane like say a Glassflugel Libelle the results would be catastrophic.  This is not a good question sorry to say.

Our wings look like the low speed ULM airfoil. Our glider is not like the zagi glider since it has a long thin body which holds the wings and tail.

I don't know much about aircraft design, but if you told me that your boat didn't need a rudder because you only needed it to go in a straight line, I would ask how you proposed to keep it on that straight line if you don't have a rudder to correct the course?

@SolomonSlow  Most boats, particularly older wooden designs, have a pronounced keel along their entire length, which will have a significant effect.

@SolomonSlow Boats, like aircraft, only require that the center of drag be behind the center of mass to continue going in a straight line. Depending on hull design some boats don't need rudders to be laterally stable. Lots of rowing boats do this - some don't even have a significant keel but depend purely on the hull being slim or a particular triangular-like shape.

@MikeBrockington, The keel of a boat will reduce its tendency to turn, but it will not bring the boat back to your intended course if wind and currents push it off course. I was hoping that the OP would think more or write more about what the requirement to fly "in a straight line" really means. Does he only require directional stability? or does he need the glider to hold a constant heading, or does he require it to follow a specific course line over the ground?

The stabilizer is meant to keep the nose pointing into the wind.
Any asymmetry in he wings/fuselage will create a tendency to yaw, you will need to compensate for that. The easiest is a fixed vertical stabilizer at the rear.

The underlying function of a VTP (not rudder) is mitigating the lateral-directional eigenmodes of the aircraft (Dutch roll, spiral divergence and roll subsidience). Unless you can guarantee a perfect launch and no crosswind, you will need some kind of yaw damping.
For a conventionally-shaped aircraft, Dutch Roll will likely be the worst offender, as roll subsidience is convergent and spiral divergence is slow.
A vertical tailplane is just one solution, however. Other things that can contribute to yaw control are positive wing sweep and active control via spoilerons or differential engine thrust. The latter is commonly employed in flying wings, but since your airfoil is not a reflex one, I take it you are going the conventional route.

It's unlikely that your project will succeed without a vertical fin.  Are you aware that there are countless radio-controlled model airplanes and gliders that feature a fixed vertical fin but no rudder?  The fin is much more than just a thing to attach the rudder to.  The rudder itself is not very necessary if the aspect ratio of the wing is not too high.  (High-aspect-ratio designs tend to suffer from severe "adverse yaw".)
But, the birds seem to be able to pull it off, so you never know.  The distribution of the "twist" or washout in the wing seems to be a key factor for them.
The literal answer to the question in the title is definitely "no".  Many successful gliders have been flown without vertical fins.  and they can do much more than just fly in a straight line.  But they don't typically look like a "normal" glider with the fin chopped off.

The birds have two things model (or real) airplanes lack: Extremely flexible wings which can generate large yawing moments (adverse and proverse, as required), and semi-automatic stability augmentation by the bird's brain. That explains why they don't need a vertical.

@PeterKämpf Also I have observed bird tailfeathers be articulated in many ways, including angling them as a group to seemingly create (and presumably cancel) yaw as well as bank.

Absolutely to the last, they definitely twist their tails to vector the lift to create a rudderlike effect.  If you watch carefully it is not obvious that the resulting "inputs" are the same ones a sailplane pilot would make with the rudder while entering a turn or exiting a turn, etc.

The V-tail Bonanza had no fin.

@copper.hat yes it does, in fact, it has two.

Coming from a very different background here - I am a keen archer.
It is normal practice (as with aircraft) to have fins (fletches) on the back of the arrow to keep it straight, but it is also a normal part of "tuning" to remove those fletches from an arrow or two, and shoot them 'bareshaft'.
The point of this test is that they are less forgiving, but because all arrows have a heavy point, the centre of mass is forward of the geometric centre, which means that the whole of the shaft acts as a stabiliser, and given good conditions, the arrow will still fly straight (and this IS largely aerodynamic flight, quite different from the ballistic flight of a bullet).
Going back to what I was saying earlier, it would be difficult to predict how much disturbance it could survive, but a simple, long straight fuselage, with no stabilising fins at all, IS going to fly fairly straight unless/until tubulance goes above a critical threshold. To be fair, this is also true of a glider with 'normal' fins, its just that the critical amount of turbulance is much higher.
One question that doesn't seem to have been mentioned is 'what is the penalty for failure?' - In a manned vehicle, failing to fly straight is considered 'a bad thing' but if your model is allowed multiple flights, then a few failures may be worthwhile if the trade-off is reduced drag.

fascinating stuff !!

Some swept-wing designs have no vertical surfaces e.g. "Horten" or "flying wing" or "Alsomitra".
NASA's Albion Bowers presented recent advances in "Why Birds Don't Have Vertical Tails" and "On the Minimum Inducted Drag of Wings".
Designing an optimal washout for a swept-wing is an advanced subject.
The simplest design is a conventional glider with a straight wing and a vertical stabilizer on the tail.
Find some easy-to-build gliders by searching: free-flight glider plans
A longer tail and more dihedral will make the glider fly straighter.

In reference to radio control models, there have been many that don't have a vertical fin of any kind.  The Klingberg Wing (from the 1980s/1990s) is a fine example; it's a pure wing R/C sailplane.  There have also been human-carrying sailplanes built along similar lines (generally, a Horten derived layout) that flew well without any sort of vertical surface.
If the glider is built for free flight (i.e. uncontrolled), it will generally need some kind of vertical in order to maintain spiral stability, but this is largely because free flight models are generally set up to fly in circles, both so they can catch thermal lift, and so they don't just fly away as soon as they're launched.  In your case, however, where you want the glider to fly a maximum straight line distance, a setup similar to a Klingberg wing (swept wing, longitudinally stabilized by tip twist) is likely to be one of the most efficient possible.

The Klingberg wing is actually identical to a Horten wing, and its yaw stability is achieved by sweep. Sweep generally costs performance, as does sideslip to which both are very prone, especially at high speed.

Yes, but you will need some alternate means of directional control in yaw. Differential drag can work with split ailerons, spoilers or spoilerons. Other options can be engineered but they will likely add a lot more weight, which you should avoid on a glider.

Weight is not a fundamental issue with a glider. It just means you have to fly faster to achieve the optimum glide angle. In fact in manned gliding competitions, the regulations specify the maximum permitted weight in a class, and competitors usually carry ballast (sandbags) to max out the weight and fly faster.

Ballast is one thing, permanent added weight is another.

Hang gliders and paragliders use a pendulum effect to mitigate yaw disturbances.  So much so in the case of paragliders, that a marked anhedral is needed to allow the pilot to steer

It  may not be whether you need one or not, it will probably be getting the right size.
Theoretically, one can design without one like a delta wing dihedralled paper airplane.
The sides of the fuselage aft of CG act as a vertical stabilizer (make them flat).
However, in practice, for free flight (uncontrolled),  it is almost impossible to get the wing drag to perfectly match for long efficient high aspect ratio wings, so on go the fin(s), but where?
Many gliders have wings longer than the fuselage.  A fin can go at each wing tip, or conventionally on top of the fuselage.  The wing tip fins will have a longer torque arm,
there for can be smaller. But the conventional tail placement has a drag saving trick up its
sleeve, putting the vertical stabilizer on top.  This uses the drag of the T tail for down force rather than deflecting the elevator. And, of course, you can combine the Hstab and V stab
and make a "Vee" tail.
So design for a vertical fin, and test in in various sizes.  If it works without one great!  If not
put it (them) on there.  That is exactly what the Air Force did when they converted the propeller driven B35 flying wing to that jet powered B49.


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What are the circled features on the upper surface of the A380 wing?
On the A380 wing are at least 3 red circle each side. There seems to be a black part inside. Is this a dip stick, or something else?

I think they are the indicators for the gear down/locked visual inspection.

Hi Ron, picture was taken on ground, gear down and locked. The gear system consists of body and wing landing gear each side. The number of 3 indicators would not fit.

The only thing I found from FCOM and 'Airplane Characteristics for Airport Planning', is that in each wing there is 'YELLOW HYDRAULIC GROUND CONNECTOR' and 'GREEN HYDRAULIC GROUND CONNECTOR'; however I am not sure if these are under the wing instead of on top.

They are likely attach points for safety harness equipment. Workers working on top of the wing attach gear that functions as anchors for lines that run the length of the wing, then attach their safety harness to the line.

Same method is used for all Airbus wings, but I don't remember similar things on the A320 wing (which I have observed a lot of times)

@ymb1 you don't need a huge orifice to support a simple line anchor. Suction is not an option, that is unsafe.

Also, if you look carefully, you'll also see that the anchors are also for the pneumatic hoses. The worker has a harness, and that has three lines, one for the tool, one to secure him to an anchor point behind him, and one to an anchor point in front of him.

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How to become pilot in India with lack of money
Hello I am from India currently I am in class 12 pursuing PCM and want to become a commercial pilot but belong to a middle class family how can I pursue my dream. I can't afford course of 60 - 80lacs.

In my country our flag carrier (Turkish Airlines) has a program, they teach you how to fly in exchange for a contract with them for ten years. After ten years you're free to work wherever you want. Maybe there is a smiliar program in your country, you might want to look that up

Airlines in most countries (outside of US and Canada) usually offer ab initio pilot programs, meaning they will train a pilot with no experience. Training will be paid for in the form of a loan which will be deducted from your future salary.
However there are some caveats. First, if you fail, you will be responsible for paying off the loan. There is no guarantee you will pass or be offered a job.
Second, these programs are highly competitive. Most programs require a college degree simply due to the number of applicants. Even then, you will have to be high in your class and be the best in all of their tests. I understand typical numbers at European airlines are 1 accepted out of 1,000 applicants.
Some people will suggest the military. Keep in mind that military pilot positions are often equally competitive. In the US, you must have a four year college degree to become a military pilot as well. I believe India is similar to the US as somebody after secondary education may apply to obtain a degree in a military academy, though that is highly competitive in itself.
Therefore, the best way may be to save money and/or get loans and gain your licenses yourself.

China has a huge shortage of pilots. You could always apply to one of their training programs. You will have to commit to work for them for a number of years, and you will have to adapt to the culture, but if you don't have the money, you will have to compromise. Or you could do what I did, find a job at a flight school and trade work for training.

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Do hospitals have radio communications with air ambulances?
Do hospitals have a sort of ATC for incoming medical helicopters? What kind of procedures do helis follow when landing at a hospital to make sure they are cleared to land/takeoff, etc?

Welcome to aviation.SE!

Kind of...
Hospital heliports are "uncontrolled airports" normally, and don't require a clearance from ATC (unless the hospital itself is within positive control airspace because it's near a regular airport). However, the helipads are private "prior permission required" airports, which means the hospital, as the owner of the pad, needs to give permission to land (same way that a helicopter couldn't just land in your back yard unless you gave permission).
The helicopter will be equipped with an FM 2-way comms radio (examples of frequencies here), that is used to talk with a given hospital's flight coordinator or EMS dispatch to coordinate arrivals and departures for logistics purposes, similar to the radio a police helicopter would use to coordinate with dispatch/911.
So if you were just buzzing around in your own helicopter and thought it would be cool to land at the hospital's helipad because you had the urge for a wonderful hospital cafeteria lunch, you'll get a tongue lashing from somebody. To do it legally, you'd have to have the
required FM radio and get permission.
There will be a normal aircraft comm radio frequency assigned for VFR advisories when coming and going, like here (where you have a VFR advisory frequency on 119.4 mHz).  The pilot will just broadcast intentions on that frequency when arriving and departing, for the benefit of any other helicopters in the area, similar to arriving and departing from any other uncontrolled airport.


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Is it true that there are VOR/DME and/or TACAN stations in the oceans?
Are there any VORs placed in the oceans for navigation. Is it true that VORs or TACANs are placed on ships to help oceanic flights, for example flights across the Atlantic?

Hello samba siva, welcome to aviation.stackexchange!

Related: How do airliners cross the ocean without GPS?

There are no ship-based VOR's or TACAN's specifically dedicated to transatlantic flights. Transatlantic flights navigate using the inertial navigation system and GPS.
TACAN's are used on board naval ships for military aircraft to find their way to the ships, but this is typically not for flights across the ocean.

There has been a FAA study for North Atlantic Long Distance Navigation (LODISNAV, part of "Accordion" research) in the early 60s with VORTAC oceanic stations. Didn't make its way to actual use. Aircraft carriers were used as testbeds.

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How are fuel tanks cleaned out?
One episode of the BBC series "Engineering Giants" featured a BA 747 undergoing a multi-week "D check". Here the inside of a fuel tank was surprisingly clean and dry (to me):

since elsewhere I've read of technicians having to wear respirators and protective overalls. Presumably the lighter fuel fractions can be driven out with forced ventillation, but is a specific cleaning process required to remove less volatile compounds?

Do you mean by cleaning an aircraft fuel tank or any vehicle fuel tank?

@FallenUser Aircraft tanks, although perhaps the approach is the same for all tanks? (naively I'd assume that regarding sticky non-volatile compounds petrol < aviation fuel < diesel ?)

FAA design regulations require that the aircraft be equipped with fuel system drain valves that allow the entire fuel system to be drained.
"Fuel System Drains -
Aircraft fuel systems must be fitted with at least one drain to
allow safe drainage of the entire fuel system with the airplane
in its normal ground attitude."
According to a maintenance person: "The residual is vacuumed or absorbed and the negative ventilation is applied. You can make entry almost immediately, though air monitoring is constant. We keep air moving through the tank anytime there is someone in the tank. "
Doesn't clearly answer the question, but this article discusses the procedures for personal protection while entering aircraft fuel tanks.

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How does the mechanical linkage of the airspeed indicator convert dynamic pressure to KIAS?
I understand the underlying principle of an airspeed indicator, ie. that it uses the Pitot-static system to measure the dynamic pressure as the difference between total pressure and static pressure.
Knowing that the dynamic pressure is $p_{d} = \frac{1}{2}\rho u^2,$ any linear variation in the measure will be a linear variation in $u^2$, not in $u$ alone. Yet the airspeed indicator markings are themselves uniformly spaced and still, they show $u$, not $u^2$. Therefore: how does the mechanical linkage convert a linear displacement (variation) in the dynamic pressure measurement $\propto u^2$ into $u$?
That is, how is the square root transformation of the dynamic pressure performed at the clockwork level of the airspeed indicator to obtain the indicated air speed?
My guess is that one of the gearwheels will be responsible for this but I haven't actually been able to find any information on this online.

Some early airspeed indicators were much simpler.


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On acquiring an aircraft for my own PPL training and later use
I know that this matter has already been discussed in several other questions but the aircraft under consideration were almost exclusively Piper Warriors or a Cessna 172s which are 40 year old designs and heavy on fuel consumption.
Instead, I am considering light sport aircraft such as a Blackshape Prime or a Sling 2, for instance. I'd prefer a Blackshape Prime fitted with a CSU.
As I am still half-way towards obtaining my PPL, my question would be the following one: would it financially and technically (from a skill-set building perspective) make sense to acquire such an aircraft and lease it back to a school to do my training?
One of the school at my airport has two Sling 2 aircraft and they're quite popular with students. Most Warriors and 172s are now in their 3rd or 4th decade and seem to have run their course. Financially, in Australia, the dual hourly rate on a Piper or 172 is in the AUD 360 - 400 range, which includes AUD 100 for the instructor whereas dual rate on a Sling 2 is just about AUD 280, which makes it much more attractive to students and at no extra expense to the school.
Would it therefore be a good idea to buy a sport light aircraft such as those mentioned and lease it back to the school? Am I missing anything that is specific to them that still makes learning in Warriors and 172s relevant? Thanks for your inputs.

Is it possible? Sure. But there are pitfalls you need to be aware of...
First, you may find it difficult to find financing for a new(er) aircraft especially if you are still a student, and especially if you are intending to offer it as a lease-back.
Then there is insurance, which for a student purchaser is going to be expensive, and even more so if you are leasing back with the idea of it being used in a flight school as a primary trainer.
The AOPA has a good article on leasebacks:
Lenders Leery of Leasebacks
AIrcraft Owners Guide to Aircraft Leasing
Turning the tables on leasebacks
Along with any number of other articles.
Another thing you need to keep in mind is that when you put an aircraft on leaseback, you, even as the owner, are subject to the same scheduling issues as renters.
The biggest thing to remember is that buying an aircraft for use in training is not a way to save money, you would be surprised at what it costs to own an aircraft, even on leaseback. You have annuals, maintenance, insurance, etc.

Thanks for the input and the pointers. It's a cost of capital calculation for me. With sufficient funds to acquire a new aircraft, the question comes down to whether placing $200k into an aircraft that will finance would make my own training cheaper. I find that the hourly hire rate quite high and wonder how much of a profit the owners make. And I don't seriously buy the argument that owners make next to nothing because they'd have no incentive to lease their aircraft otherwise. Surely it must be advantageous to schools to have a newer aircraft over old ones, wouldn't it?

Actually it is advantageous for schools to use older, common aircraft. They are cheaper to maintain, fix, acquire, and insure. Your rates in NZ are high, in the US, a G1000 172 is about 230 AUD and older 172P is around 160 AUD. Owners really don't make anything with lease-backs, the school takes a cut, the rest goes to your payment/insurance/annual costs (plus however you work out the 100 hr inspections) and "overhaul fund", which comes much quicker in a leased aircraft.

Interesting. I was under the impression that maintenance on a Rotax or Lycoming engine would be the same irrespective of the aircraft and that newer aircraft would be less complex to maintain, thus cheaper too. I need to investigate further locally here in Australia why rates are so high anyway. Also, I tend to see the opportunity to fly a newer aircraft as a win-win for both the students who pay less and schools which can offer cheaper rates while retain their margin. Lastly, I believe that schools are sticking with old planes because they lack the funds to replace them.

@沖原ハーベスト: Another thing to consider is how much you expect to use the aircraft.  I have always heard (though I have no actual evidence) that a plane ought to be flown a minimum of 200 hours per year, otherwise it can suffer from "ramp rot".  So either leasing it to a flight school or a partnership are ways to increase hours flown.


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Advantages to doing an initial instrument rating training in a Cirrus over a conventional aircraft?
I live in Australia and I'm in the process of choosing a school for my instrument rating. I need feedback from the many of you out there with IFR experience willing to share their thoughts.
I'm going to do a single engine instrument rating because I am a just private pilot with no immediate plans of doing a CPL or flying multi engine aircraft at the moment. I have CSU and RU endorsements, have flown VFR to this day on a basic and complex aircraft. There are a few schools that I'm considering, with the only real difference among them boiling down to aircraft and, of course, total training costs.
1. Towards the top end, I could train on an SR20 and brand new full
    motion simulator in a posh school.
2. The middle range would be on an C182 or a PA28R and standard
    simulator.
3. The lower range would be on an IFR rated C152 + time on a complex
    aircraft, and again standard simulator.
All up, the costs would go from simple on the C152 to (almost) double on the SR20.
Here's my call for advice: Other than the fanciness of flying in an SR20 over a C152 and learning in a shiny school,
What are the real, concrete benefits of doing an IR in an SR20 over a more conventional aircraft?
On the one hand, the C152 has analog instruments while the SR20 is all glass and has autopilot which, I understand, comes down to personal preference. Another key difference is speed. I'd say that flying more slowly might be an advantage to stay "ahead of the aircraft" but then again, that might be beside the point of IR training. I'm the super lucky position to be able to afford both but I still want to make a financially clever decision as I'm not the kind to spend money unnecessarily. In hindsight, that's how I did my PPL and it served me well.
A great many thanks for your much valued answers.
PS. Another factor that does play a role is obviously instructor experience and their availability.
PPS. A definite minus for the SR20 is the "requirement" to do the CSIP endorsement which puts the total costs just shy of that of a multi-engine endorsement on the Seminole or on the DA42 + IR.

I think the answer depends on the kind of airplane you will be renting after you get your rating. If the planes available to you have steam gauges, then go that route. If you have access to planes with a G1000 or other glass panels then train in the Cirrus.

What exactly makes the Cirrus not a "conventional" aircraft?  Looks perfectly conventional to me: https://cirrusaircraft.com/aircraft/sr20/

@JScarry My impression is that transitioning from analog gauges to glass panels will be easier than the other way around. I also don't want to be limited to a specific kind of aeroplanes when I obtain the rating.

@jamesqf That's the only small single engine aeroplane out there that operators require you to have a CSIP certificate to fly, which makes it more akin to having a type rating for practical purposes. Which other aircraft of that class takes 3 days to transition to, really? I'm not suggesting that there isn't a bit of marketing involved here but the whole approach indicates that their aircraft are not "what you already know".

Yeah, but it's a light four seater.  It really doesn't matter which plane you use for your IR.  I'd recommend using a steam gauge relic because it is more difficult, but that's just me.

There aren't any. Unless you are planning on purchasing a Cirrus, you'd just be burning money for no good reason by training in that. An instrument rating is an instrument rating regardless on what aircraft you train. What is important is the quality of the training, ground and flight. If you think about it, I am quite sure you can find better ways of spending the money you will save.

The other thing is it's just "too easy" when you learn on  an airplane with one of the latest avionics suites that require little in the way of mental situational skills.  Move onto something with steam gauges later, and you'll be lost.

@JohnK Yes, that is a very good point. It's a similar reasoning to why I recommend aspiring pilots get their glider ticket because their powered aircraft ticket. Learning how to fly in a glider really teaches you to truly fly, and to think well ahead of the aircraft, because you only get one chance to land.

I understand the point you're making here. I for one cannot say that a Cirrus aircraft is my ultimate goal, I'd rather be conversant with a wider range of aircraft to be honest. In terms of performance, I'm only afraid that a C152 will be too modest with two adults on-board. Won't learning all the procedures on a C152 be a problem when transitioning to a faster aircraft?

@JohnK Could you concretely give an example of something that the G1000/Perspective would chew out for you needed for IFR that you would otherwise have to calculate mentally? Like calculating intercepts, 1/60, ... ?

I would say it's mostly the large screen attitude display with synthetic vision that looks like a TV image vs a small gyro horizon and separate gauges.  If you learn only on the new and have to cope with old one day, having never developed the scanning habits required with steam gauges, it would be a problem.  The Cirrus has a Flight Director.  You need to learn to fly the needles so you aren't dependent on the FD.  Although 2D maps are pretty much universal even with the most basic GPS nav, it's good to forgo that and learn to mentally situate yourself, like you had to do in the "olden times"

of course it's also easy to "get lost" in a cockpit with just some television screens and a bunch of buttons where good old switchology and steam gauges don't require digging through multiple layers of menus to get the option you want...

Cheers to @JohnK, jwenting and Juan for your inputs, I appreciate. I'll go the old fashioned way and learn on steam gauges.

You're very welcome and good luck with your training @VH-NZZ.


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Ground Speed On Approach
I'm not a pilot, just a bit of frequent flyer and moderate aviation enthusiast. I sometimes get on Flightaware and check on the flights I frequent and see the path that was taken and flight time. I noticed today on the track log that a ORD-GSO flight airspeed dropped below 100mph while lining up for the approach. I had never seen this before and was curious to how often this happens? Isn't this dangerously slow even for the short time?
https://flightaware.com/live/flight/ENY3619/history/20190517/1655Z/KORD/KGSO
Thanks!

https://aviation.stackexchange.com/questions/2269/why-do-aircraft-on-flight-radar-24-jump-around-randomly-sometimes

If you look at the FlightAware track during the time the speed drops, this happens just as the aircraft makes a sharp turn. Given that the data comes from FlightAware's multilateration, this strikes me as a data error rather than the actual speed of the aircraft.

Welcome to aviation. SE! This question might be helpful. A key point is that speed over the ground and speed through the air are two different things, and only airspeed is important to keep flying safely. There are also issues with how FlightAware displays information but that's a separate topic.


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Can diplomats be allowed on the flight deck of a commercial European airline?
If a diplomat were to request access to the flight deck with proper identification, would he/she be allowed to visit the cockpit of a commercial airliner during flight?

I see no reason why.

A diplomat would likely have as little or as much access to the cockpit as any other passenger.

Not on the two international 747 carriers I flew for.

One word comes to mind: WHY?

Presumably he's thinking about Diplomatic Immunity, the diplomat's literal get-out-of-jail-free card.

@nick012000 That's the thing, though - it's only usable if you are in jail (or at least in danger of getting put into one).

@DanilaSmirnov Trying to force your way into the cockpit of an aircraft is usually a crime punished by a rather significant prison sentence. ;)

@nick012000 The key word here is "trying" - it's not like saying "hey guess what, if I break down your door I won't get punished" would have pilots going "oh okay, we'll allow you to come in then".

@DanilaSmirnov Not really, works all the time on parking tickets.

Diplomatic immunity means the person might not be prosecuted (immunity can be rescinded) but it does not mean the person will not be hog-tied with nylon straps, thrown into a toilet and locked in there until the airplane lands, then handed over to law enforcement, after which ultimately the person will be declared persona-non-grata and thrown out of the country like a sack of potatoes. :) It is also quite possible that one of the pilots will draw a firearm, give one and only one warning, and end the diplomat's status with extreme prejudice. Shoot first, ask questions later.

Kolindar, welcome to the site!  The simple answer to your question is "Of course not."  The days of anyone (at all) "visiting the cockpit" are long gone, ancient history.

The title question ("Can diplomats be allowed") is different from the body question ("would he/she be allowed"). The former seems to be asking about the crew's discretion to allow a visit if they want to, while the latter seems to be asking if a diplomat is entitled to be admitted on request.

Crews only have as much discretion as their employer grants them.

Generally, airlines are required to have content in their ops manual clearly stating who is entitled to flight deck access from the point the engines are started until shutdown. In some countries, such as the UK, airlines are required to limit access only to essential personnel, and foreign airlines must follow the rule while in UK airspace. I would find it rather disturbing that an airline would allow access to the flight deck during flight ops to someone just because they have a diplomatic passport, given that some countries play it fast and loose with such documentation, and flight crews are not equipped to validate a passport.
SKYbrary is a wiki created by the European Organisation for the Safety of Air Navigation, International Civil Aviation Organization, and the Flight Safety Foundation to create a comprehensive source of aviation safety information freely available online. Its guidance on this subject is crystal clear:

In the air, procedures vary from airline to airline and from region to region, but the principle that only those with legitimate need must be permitted flight deck access must be paramount. Beyond the pilots at the controls, this will include relief, check and training pilots. Exceptionally, such flight deck occupancy may exceptionally be extended to include other specifically-authorised employees of the operator - pilots, cabin crew and maintenance personnel. Flight Operations Inspectors carrying out observations on behalf of the State Regulatory Body may also be permitted access at the discretion of the aircraft commander subject to valid identification being presented prior to entry approval.

"I would find it rather disturbing that an airline would allow access to the flight deck during flight ops to someone [...]" 30 years ago getting access was not uncommon.  My parents and grandparent all have been to the flight deck of large commercial airliners, even in european (german to be precise) airspace. I would guess 9/11 changed things in this regard drastically.

@Polygnome That was exactly what changed after 9/11. It used to be that every kid on a plane whose parents asked nicely got to see the flight deck.

@DavidRicherby They still can, just not between startup and shutdown of the engines.

@JuanJimenez True. But going during the flight was the big thing.

Yes. Last time I did it was 2009 on a flight from São Paulo to Córdoba, but only because at the time I was an employee of American Eagle and a pilot. In Brazil pilots are gods, right up there with judges and doctors. They were tickled that I was going to Argentina to ferry a 1948 Stinson to Buenos Aires with a friend.

authors: Bob Jarvis - Слава Україні


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How could I find the air velocity and lift force?
As shown below I have this information as shown below in the picture. I got the density according to the ISA standard  = 1.225[kg/m^3]  and  =  (−0) is calculated as below :
α=−4: CL=0
α=16: CL=0.025∗(16+4)=0.5 according to the diagram below:
I just want to know how to find the velocity and lift force?.
The lift force law is like this =(1/2)  ^2

The indicated airspeed is the result of computation using basically the static pressure from the static pitot and the dynamic pressure from the dynamic pitot.
Further to apply your formula in addition to CL and the density, you need to know the active area S of the wings which at high speeds may depend on the speed itself, so you need the wings specific data.

So, wing surface is not the same of s in the equation?.

It is, but up till a speed limit

I got it. Thank you so much sir


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How could I find  lift coefficient slope?
I'm trying to find  lift coefficient slope through the below diagram, could anyone explain for me please, how could I find it?
by the way, I depend on this equation  =  (−0)

You can eyeball it from the plot, it is the slope of your curve, rise over run. Your cL goes up .1 for every 4 degrees, so cLalpha is (.1)/4

@MikeY Thank you so much sir

Basic maths:
$\alpha_0$ = point where the line crosses the x-axis = -4
$C_L(\alpha)$ is linear, so take any two points, e.g. (-4,0) and (16,0.5)
$\Delta y$ = 0.5 - 0 = 0.5; $\Delta x = 16 -(-4) = 16 + 4 = 20$
$$C_L = \frac{0.5}{20} * (\alpha + 4) = 0.025 * (\alpha + 4)$$
Check:

$\alpha = -4: C_L = 0$
$\alpha = 16: C_L = 0.025 * (16 + 4) = 0.5$

Thank you so much sir.

The lift coefficient slope is the ratio of a small increment of CL to the corresponding small increment of AOA. Since your curve is reduced to a straight line the result of the ratio would be the same either for small increments ratio or for large increments ratio. To calculate the slope ahead of stall you may go from alpha = -4 to alpha = 16; the corresponding CL goes from 0 to 0.5
So the slope will be (0.5-0)/(16-(-4))=0.5/20
If you go from alpha =0 to alpha = 16, CL will go from 0.1 to 0.5 and the ratio is: (0.5-0.1)/(16-0).
Both examples will give you the same result as you may check.

Thank you so much sir.


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How can I fix the stalling of an RC plane after the addition of floats?
I'm modifying a RC plane into a bi-plane with floats and it keeps stalling. I don't have a bigger battery or better motor to add so how do I fix this? This is the biggest challenge I've ever faced.

Are the floats just hunks of foam? How do you know it's stalling and not just way too much drag?

From the photos it looks like you've taken the wing of some other model, lashed it to the fuselage with elastic bands, and slapped on some bits of foam to act as floats. Many things could be wrong with this, and there may not be a simple fix. Find a local aeromodellers' club and take it along. They'd be much better placed to make suggestions at first hand than we will.

Do you not have an elevator?  Can't you just give the plane some nose-down trim with elevator?  I'm suspecting that you do not have an elevator; if so that is important to share w/ us.  In fact I'm suspecting that this plane has NO moving flight controls and is controlled ONLY by differential engine thrust from the 2 wing-mounted engines-- is this true?  Maybe you could add an elevator even if it just something you set on the ground at a fixed position for trimming.  Not quite enough info in the question as of now to justify a full-fledged answer but--

Has the airplane ever been flown in the current configuration except for no floats?  I suspect you added the lower wing and the floats all at the same time?

Is the center propeller functional, or fake? What is the pin with the white ball head next to the propeller?

Fun question where we can finally submit structural ideas without the "Ask a certified technician" disclaimer. Welcome to Aviation SE!

Now the title has been edited to ask a substantially different question than I originally understood to be asked-- you wish to lower the stall speed?

"s the center propeller functional, or fake? What is the pin with the white ball head next to the propeller?"-- good eye.  If the center prop is fake, get rid of it to reduce drag.  That may not decrease the stall speed per se, but it will help you stay above stall speed w/ what engine power is available to you, while maintaining (possibly) level flight.  Let us know if the center prop is fake..

Your model is based on the FX-803 Piper Cub model shown in this video. It's made from expanded polystyrene wings and fuselage, with a two channel radio that controls thrust from two motors mounted below the wing, with overall thrust controlling pitch and differential thrust controlling yaw. There are no moving control surfaces, and the propeller on the nose is a cosmetic windmilling attachment.
Your extra wing, lashed on with elastic bands, may or may not produce lift, but adds additional weight and drag below the thrust line, inducing a significant nose down moment. Your carved foam floats add additional drag even further from the thrust line exacerbating the nose-down problem, and further increasing the weight.
The original model was built and trimmed to give flying characteristics that could be controlled by simple thrust adjustments. There is no moving surface with which to counter the added drag, and even if there were, it is unlikely it would have sufficient authority to overcome the problem.
The modifications may also have moved the centre of gravity significantly, possibly beyond the point where it is fixable.
The model shown in the video has sprightly performance on limited power. The additional weight and drag you have added could easily overwhelm the available power.
You could try adding a fixed elevator to provide significant down force at the tail, but this will further compound the drag issue, and could also affect centre of gravity.
Realistically, I doubt you will be able to get this to fly. If you do, please come back and post a video!

This plane appears to have no moving control surfaces at all-- it appears to be controlled purely by differential thrust from the two wing-mounted motors.  You could consider modifying the horizontal stabilizer to give the plane an elevator, even if just works as a ground-adjustable trimming device. You need to fix the elevator  in a slightly lowered position to counteract the stalling tendency you are experiencing.  Don't overdo it!  It could be as simple as piece of stiff cardboard taped to the back of the horizontal stabilizer, that you can bend into a lowered position. In fact it looks like you may have already done something like this with the vertical fin, to give some right rudder trim.
Or you could just try moving the CG forward by adding weight to the nose.  This is probably the best solution as will enhance pitch stability as well as help address the trim issue.  Again, don't overdo it!  Small changes will be best--
Or try a combination of both approaches.

It is hard to give authoritative advice without even knowing the relative incidence of the two wings. Maybe one stalls already when the other is just starting to produce lift? How is it flying without the floats? Since their drag adds a nose-down moment, an elevator should definitely be added.

OK! Is there a doctor in the house!
Try moving the lower wing back until it stops pitching up. "Staggering" the wings may also
reduce interference between the two, which may be part of the problem once it starts to pitch up.  It should fly better overall with the lower wing further back.
Try this modification and hand launch to test. If it works, then reset your floats as needed.


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How is the aircraft stand vertical lux measured?
How is the vertical lux measurements taken for aircraft stands? Is it 2 m above the ground with the lux meter facing the light source, or parallel to the centreline?
What is the purpose of the lights on the stand? Is it for the ground services or the aircraft?

In 2m height, from two sides minimum, best if they are perpendicular to the centerline

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

@Sean It actually does provide an answer to the question. Peter, welcome to Aviation.SE! It sounds like you have personal experience with these measurements. Could you expand your answer a bit and maybe include a reference?

Hi and welcome to aviation.SE. Don't hesitate to check the help center to @Bianfable 's comment about answer expansion.


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What is this airplane?
Found this old pic of an aircraft that used to service the north. Was wondering if anyone could identify, or had registration information. It would have been in service sometime between 1950-1970.

Not a complete answer but it's a Beechcraft Queen Air, which puts it 1960 the earliest.

From this link http://www.beechcraft.com/customer_support/technical_publications/docs/nontechnical/serializationList.pdf the sales year of this serial # was 1969+ (near the end of my time line). This pic must have been taken when my relative returned to the north in the mid-late 80s before it was de-registered in 1988.

Gosh -- an aircraft just for White Walkers!   :-)

Its a Beech Queen Air (note the piston engines) the precursor to the king air.

Dave, As a novice I did not notice. Thx for pointing that out.

The main difference is that the Queen Air can move any number of squares horizontally, vertically or diagonally, whereas the King Air can only move one square at a time but has the additional safety feature that it can't be moved into the path of another plane.


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Why is the intake of the 757 (RR) engine slanted?
I'm sitting looking at a 757 with Rolls-Royce engines and just noticed that the intake is slanted forward by 5-10 degrees. Anyone know why?

(wikimedia.org)

This is the case frequently, as the aircraft doesn’t have the same pitch angle on ground while accelerating, or at rotation, or at climb or at cruise. So the intake slant is calculated to the best appropriate as an average. As a summary this is not specific to this engine on this aircraft


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Can autopilot navigate automatically?
When the pilots enter their flight plan into the FMGS, the route will be shown on the ND. Can the autopilot automatically turn when needed with the given plan, or the pilots have to manually adjust the heading everytime?
And if possible how do they can manually turn the aircraft within autopilot when needed like: landing, etc.

Generally speaking (not specific to Airbus), what the layman refers to as "autopilot" is actually three logical systems:

The Flight Management System (FMS), which  figures out where the plane is in relation to the supplied flight plan.
The Flight Director (FD), which figures out how to navigate the plane to where the FMS wants it or according to manual inputs.
The Autopilot (AP), which manipulates the flight controls to follow the FD.

Generally, the FMS and FD will be engaged for the entire flight, but the AP is not engaged until after takeoff and is disengaged shortly before landing.
While the flight plan is issued before takeoff, it is frequently amended by ATC during flight. When this happens, the pilot just enters the new data into the FMS and lets the FD and AP adjust as needed.
However, sometimes ATC will issue "vectors" to aircraft, which is an instruction to fly a particular heading or track. To comply, the pilot dials that setting into the FD control knob and changes modes so it follows that manual input instead of the FMS. When ATC puts them back on course, the pilots simply switch the FD back to following the FMS.

Since you tagged airbus, I will answer for the A320. The following image from the FCOM shows the FCU (Flight Control Unit) on the glareshield:

This is where all inputs for the autopilot are made. The second knob is the HDG OR TRK SELECTOR KNOB, which allows setting a heading. In general these knobs work as follows:

To make the autopilot follow the flight plan from the FMGS, you push the knob in. If you want to manually deviate, you pull the knob out, the dashes will disappear and show a number and you rotate the knob to adjust.

Thanks, this helped me alot.

Yes, RNAV autopilots can fly a given route automatically. A pilot can disengage and fly by hand at any time during the flight and the flick of a switch.

Sometime during approach, the pilots turn the aircraft heading from the FCU. What will  they do to override the RNAV?

turn the autopilot off and use the stick, or go from RNAV to Heading mode and give the autopilot a heading to fly.


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What does 1FD2 mean?
On the EFIS of Airbus you can see 1FD2 on the autopilot section of the FMA. what does it mean?

It means that both Flight Directors are engaged:

Flight Director (FD) Engagement
The FDs are engaged automatically whenever the FMGC powers up.
Ground Engagement

The symbol "1FD2" appears on both PFDs.
No FD bars appear on the PFDs. The PFD displays FD orders when a mode is active on the corresponding axis.
The FCU windows display dashes.

(A320 FCOM Autoflight - Flight Guidance)
It will look something like this:

The pilots can disengage one or both FDs. In this case -FD2, 1FD- or nothing will be displayed.

Manual Flight Director Disengagement
One FD off:

The FD bars no longer appear on the associated PFD.
The corresponding FD is disengaged.

Both FDs off:

The FD bars disappear on both PFDs.
If no AP was engaged, lateral and vertical modes disengage. The A/THR, if active, automatically reverts to (or remains in) SPEED/MACH mode.
If one AP was engaged when the FDs are switched OFF, this AP remains engaged in the active modes but the FDs are no longer displayed.

If one FD fails, the other one will be used to provide guidance on both PFDs. In this case 1FD1 or 2FD2 will be displayed.

Automatic Flight Director Disengagement
If one FD fails or one FMGC is not valid, both PFDs display the remaining FD.

To add: 1FD1 means both the captain and first officer PFD receive information from the flight director 1. 2FD2 means both use flight director 2. This is the case e.g. if one FD has a malfunction

@Jan Thanks, I added it to the answer.

@Jan Yes, this site lists them all but I'm not sure how authoritative the site is. It seems to be a preview/demo of their smartphone app about A320's displays and panels. But it looks good, though.

@PerlDuck My quotes and images are all from the FCOM. Interestingely, the FCOM as far as I could find does not mention modes like 2FD-, but that does not mean they don't exist. It would make sense after all...

@Bianfable As said, I don't know how reliable the site I linked to is. I also wonder why all seemingly official manuals in the internet look like faxes or otherwise pirated scans of the "real" documents. Maybe I'll post a proper question on this...

@Bianfable I've seen plenty of mistakes in the FCOM, too. I've seen 2FD2 in a video where the FD 1 CB tripped during takeoff. But I'll probably never find that video again, watched at least 15k videos after that and the Youtube history only goes as far as 5000 or so. :)

From a technical standpoint this makes sense: Dash = this side FD is not selected on by the pilot. 1 = FD1 powers this side. 2 = FD2 powers this side. Default is 1FD2, so left is FD1, right is FD2. If one FD has a fault both see the remaining FD. So 1FD1 and 2FD2 should exist as well as 1FD-, -FD1, 2FD- and -FD2 (when one pilot selects his/her FD to off. -FD- is not displayed afaik.


text:
Why is a weight and balance graph lozenge-shaped?

(fireair.co.uk)
Why is a weight and balance graph lozenge-shaped? I have tried to find the answer but it seems to be really hard to find. Why is it not a square?

What aircraft is it for?

@757toga That's a valid explanation I believe, and you see that cutout (or whatever it s/b called) on numbers of aircraft types. The question is a bit ambiguous though. I interpreted it as asking why the c.g. location lines are at an angle rather than straight up since showing them as 90 degrees vertical would make it rectangular save for the cutout. Perhaps the OP will see this and elucidate.

That's also an interesting question: is the horizontal spreading of the cog lines meaningful (perhaps indicating more accurate numbers at the wide end?), or is it just for effect.

@757toga - unless I'm reading that plot horribly wrong, the CG limits do not move based on aircraft weight.  The fore and aft limit lines are marked and 83 and 93 inches aft of the datum line along their entire length.  Normally, you see plots like this with axes of moment and and weight, or, if their are in terms of CG location and weight, the sides are vertical.  Seems to be for effect (exaggeration of limits at the upper end of the envelope).

@757toga -- yes, it does: my apologies for the disconnect, but I was referring to the left and right limits of the plot (with the exception of the "cutout" in the upper left).  That cutout makes sense, but the rest of it seems plotted to exaggerate the changes in the upper portion of the envelope.  Forward CG limits, I think, are normally based on elevator control authority as you said before.  I think that the plot itself is quite odd and is not representative of CG envelopes because of these angled lines...which I think might be what the OP is trying to figure out.

@757toga -- that's what I think too.  And that's why I was confused by the chart as I've never seen a W&B chart like this before.

They come in many shapes,not just lozenge.  Google "aircraft center of gravity charts" and you will see many examples.  The shape is determined by the aircraft manufacturer.

The chart is for Piper PA-28 Cherokee Warrior II. POH can be found on multiple sites, chart is on page 6-14.

In a strict mathematical sense the graph should be extended into a complete right triangle, not a rectangle. However there are practical limits on how far forward you can fill the compartments so the graph can be cut off at 83 inches in this case. The top is clipped because increasing weight above that point reduces performance and safety margins below design intent and angers bureaucrats.
The reason for a right triangle is because the acceptable location of the center of mass is more critical at increased gross weight. When the plane is very low weight the center of mass can be very far forward and not overwhelm the tail down force and leverage. At high gross weights the tail needs more leverage to counter the nose down moment, so the forward limit of the center of mass must be brought back closer to the center of lift. There is no angle on the aft limit side of the chart because moving the center of mass behind the center of lift, at any loading, will make stall and spin recovery impractical or impossible on a traditional wing and tail layout.
The slight radial flair in the particular chart pictured is simply styling.

"The slight radial flair in the particular chart pictured is simply styling" is not quite accurate.  This type of graph is the OEM's choice; many are in standard Cartesian coordinates.  The reason for this style is for the purposes of loading in various manners.  Regardless of the Gross takeoff weight, the fuel burn will be the same.  If you create one fuel burn curve, this type of chart allows you to slide that curve to a new gross weight, and you will immediately see if the CG will go out of the allowable area.  On a Cartesian chart, you have to plot every point and connect the dots instead of just sliding the whole curve.  This is very useful on swept wing aircraft that have multiple tanks that are expended in a specific order. 707 has 7 tanks; a good example.
There has been discussion of moment and downforce capability of the horizontal stabilizer.  Most of this is good, but you need to take that one step further.  There are also structural limits at certain points of the airframe that cannot be exceeded.  Too much downforce from the HorStab could exceed those limits.  Conversely, a CG too far forward could exceed bending moment allowances forward of the wing root.
To build a chart, check out Vector charts in  T.O. 01-1B-50 (2005), available online.

Welcome to aviation.stackexchange.com!


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What is this 11-engine airplane?

I thought it looked similar to an An-225, but there are too many engines.

Please make some basic research before posting here. Auch aircraft only exists in fiction


text:
What repair can be done on this wingtip? (777)
The accident happened in August 2012 and broke the wing of the Boeing 777-200 passenger jet. While taxiing at Shanghai's Pudong airport, its wingtip hit the tail of another aircraft.

What action need to be taken towards this kind of damage?
What manual is used as reference for this repair or replacement?
(Is it Structure Repair Manual or Aircraft Maintenance Manual)

9M-MRO - the aircraft that flew MH370

what do you mean by "the aircraft that flew MH370"? what i found on the internet is this aircraft is mh307. or am i in the wrong here? http://www.dailymail.co.uk/news/article-2576353/Malaysian-Airlines-Boeing-777-centre-crash-probe-collided-plane-two-years-ago-breaking-wingtip.html

I was just pointing out that the exact aircraft in the photo was repaired, went back to flying, and a few years later went missing as MH370.

@Ben well. i learned something new then. so this means that the article is misleading. thank you for the info.

@cat You seems to be confusing flight number and tail number, there's a difference.

@Notts90 yes I am. Does that mean the tail from a different aircraft? is there a source for me to read it?

@cat you might want to ask as a separate question, but essentially a tail number is unique to an aircraft in the same way a license plate is unique to a car/bus (registration number in U.K.). The flight number is specific to the flight being flown, i.e. the 0845 flight  from London Heathrow to JFK would have a specific number regardless of the actual aircraft flying it, it’s roughly the equivalent of a bus route number.

I'm pretty sure they can replace a whole piece of wing.

@ManuH is replacing the whole wing is more relevant and cost efficient compared to just repairing the wingtip? Which manual do you need to refer to in this case?

@cat Nope, but replacing a part of it is a kind of reparation. And this is a comment, if I had references, I would have put it as an answer.

Duct tape.  Lots of duct tape.

@Sean so that was my problem. i'm not using enough duct tape to repair it. thanks chief

"What action need to be taken towards this kind of damage?"  The first action that needs to be taken is to ground everyone responsible and retrain them, if possible.  Then perform adequate testing of their skills.  That's a big "oops".

What action need to be taken towards this kind of damage?

The aircraft will be grounded immediately and damage like this needs to be repaired in a timely fashion to get the plane back in the air and making money once again. Its worth noting as well (under FAA regulations) that you would also be in breach of § 23.1385 Position light system installation as the position lights are usually installed in the wing tip.
For damage like this Boeings AOG team will be brought in to repair it

The Boeing team isn’t called in for everything. Airlines have
  incidents every day, Testin says, and most airport ground crews can
  handle routine repairs—a window cracked by a bird, a component failing
  calibration. An AOG intervention is required for the big things: an
  airplane off the end of a runway, landing gear accidentally retracted,
  a flaming tail drag, two 150-ton behemoths kissing wingtips on the
  ramp.

Since it's Boeing themselves coming in, they may use a variety of reference material to fix the damage and it really will vary case by case depending on what needs to be replaced. In this case the damaged metal will be removed until they get to an area at which they can begin to joint on a new wing tip.
I cant find any great examples of wing repair being done on jumbos as its most likely done behind closed doors but here is a great video of it being done to a small aircraft generally speaking the fundamentals are the same as the designs only change in size. Remove the damaged skin, get the wing down to the ribs/spars, repair/replace ribs if necessary, re-skin wing.

There's a National Geographic TV episode that follows Boeing's team doing a repair of an aft pressure bulkhead on a 767. While it's obviously not the same situation as repairing the specific damage here, watching it would give you an idea of how these types of repairs are carried out.


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How to measure thrust produced from combustion chamber of Gas Turbine Engine?
I'm conduction a scale model experiment of thrust production in combustion chamber by using different types of fuel source.
Comparing the thrust produced by using hydrogen gas, kerosene and petrol.
Specific energy:
Hydrogen gas = 142 MJ/kg
Kerosene = 42.8 MJ/kg
Petrol = 46.4 MJ/kg
What are the instrument to be use for measuring thrust output of the combustion chamber through combustion of the fuels?
What values do we measure? (eg. airspeed at output of combustion chamber/ temperature/ thrust)

Does your chamber have a nozzle? The nozzle of jet engine is what produces most of the thrust. A combustion chamber by itself will just raise the temperature and have little effect on pressure and velocity

@DanielKiracofe planning on doing a can type combustion chamber. the design would be similar. but size may differ a bit. i dont know what instrument to use for output thrust measurement.

What is the purpose of this exercise? While thrust is ultimately generated because energy is added to the stream in the combustion chamber, how much will be generated depends mainly on the temperatures (inlet, peak and exhaust), design of the other components (nozzle, turbine and compressor), ratio of the heat capacities of the working fluid, and also the flow stream (accelerating already fast stream takes more energy for the same momentum). Most don't depend on the fuel (temperature is usually material-limited) and what does (the energy) is easy to derive.

@cat you may want to look into LNG.  It is cheap and falls in between kerosene and hydrogen in specific energy with reasonably good energy density.  Space X seems to like it.

I suppose you'll have better luck finding an answer in an engineering forum.

Option 1: Thrust is a force, and Force = mass * acceleration, and acceleration is change in velocity.  So you need to measure the mass flow, the velocity upstream and the velocity downstream.  It is probably sufficient to just measure the air mass flow upstream, and measure the fuel flow, and not measure the air mass flow downstream.
Option 2: instead of measuring the air, measure the reaction force.  i.e. at some point, you have to support your combustion chamber.  It will be bolted down to the floor somewhere.  Where ever that is, get a load cell. That is a thing that directly measures force.
But again, with either of these two options, I would expect that your measurement thrust measurement will be pretty close to zero.  A combustion chamber will not generate a large thrust on its own.  You need a nozzle in order to generate a significant amount of thrust.

Always go fro option 2 I reckon, no substitute for direct measurement of the variable.

options 2 seems to be more suitable for my experiment. and i had made a few tweaks for the set up. instead of going for GTE combustion chamber, i made a pulsejet and use the same 3 diff fuels as variable

First, there is a real danger of an explosion here if the fuel air mixture is too lean.
Long ago my science teacher filled a coffee can with natural gas. The can had a little hole on top and one near the bottom (natural gas is lighter than air). He lit the top and sure enough the flame burned down to blue and then the mixture in the can (mildly) blew up.
You may find thrust will be dependent on how much AIR you can ram into the container.
All three of those fuels will generate thrust.  Much of your question is already known and can
be sourced through rocket databases under specific impulse.  Not surprisingly, hydrogen/LOX (liquid oxygen) gives the highest value, but other liquid fuels give a higher energy density (per volume). Many 1st stages on rockets use kerosene.

Since this doesn't answer the question (How to measure thrust produced from combustion chamber of Gas Turbine Engine?), it might be better suited as a comment.

On a small, lab, experimental scale you simply see how much weight it lifts, just like James Watt's horse.

And now you have the more answer-like part as a comment :) If you were to elaborate on that in the body, you'd have a credible answer.

@AEhere the point is before one goes into their garage and tries something dangerous a little background research can be very helpful.  One need only look at the specific energy data already provided, along with specific impulse data from rocketry.  For airbreathing engines (from cars right on up to jets) getting as much air in is as possible the name of the game.  Rather than measuring thrust from compound X, one need only measure its caloric (heat) output.  Burn rate may be significant too, as well as boiling point.  And for thrust, see how hard it pushes a piston!!!

I don't disagree, but: This site is all about getting answers. It's not a discussion forum. There's no chit-chat. This is an excerpt from the site's tour (https://aviation.stackexchange.com/tour).

Oh, and you own the place?  Sorry, I did not include specific thrust measuring devices (or theoretical ones) because energy content of propellants is already known and dangerous testing of "thrust" to prove it is not necessary.  Appreciate and respect your opinions, why don't we see what others think.

I just care about the stated goals of a site I spend some time on. My apologies if that somehow irks you.

No problem, could not resist the emojies.


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what Jobs can I get without atpl?
I wonder what jobs I can get if I have ppl and cpl but no atpl?
is it possible to earn money from holding these licences?

Which country are you asking about?

This is not a duplicate as this question asks what work you can do on a CPL. It is completely different to what work you can do on a PPL.

Yes.  See FAR 119.1.  They have a list of other commercial operation you can do with a CPL but not an ATPL.


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What are these lumps on the top side of the wings of military aircraft?
There is an online video game called War Thunder that lets you fly various planes from roughly the 30s to the late 50s. It has some pretty detailed models, and I've noticed these lumps on the wings of many planes. The planes are partly modelled on the interior and can be seen in what's called X-ray view. I've noticed that many of these lumps are placed right above where the base of the plane's gun/cannon is. This has led me to believe that they might be placed in these positions to cool the guns as air is swept over these lumps. But it turns out that in many cases these lumps aren't placed where the guns are and seem not to have this purpose. Here are some pictures of what I've talking about, I have circled them in black.
Examples of where they appear over the guns:
Focke-Wulf 190

Hawker Tempest MkII

Brewster F2A Buffalo

Sukhoi Su-6

Examples where these lump wing features don't appear above the gun/cannon:
Supermarine Spitfire

Grumman F4F Wildcat

Gloster Meteor

de Havilland Venom

Note that the last two planes are jets and have their guns mounted completely in the centre of the plane, on the nose (ie., there are no guns in the wings). Also, I've noticed that for planes that have no guns mounted in the wings only British planes (in the game) have these, namely the two jets.
I'm am wondering what the function of these things are, and what they are called, if anything? Do they serve an aerodynamic function or are they maybe to cool other parts within the wing?

Although the pictures you used were essentially accurate, they are screenshots from that game war thunder right? Just for future reference, don't take what game developers (ESPECIALLY Russian developers of free games) model into their vehicles as fact and expect them to be accurate. I don't really play games, but I've heard some poor comments on war thunder's models specifically, so first try to find real life equivalents of the plane in the game you have the question on and try to refer to those. Interesting question though!

They are fairings for one thing or another that projects above the wing skin.  Part of a gun or ammo feed system, fuel cap, wing fold mechanism, head of a big bolt, whatever.  Usually, components are designed in the original versions of the aircraft to fit within the wing profile, but mods and add-ons later introduce bits that project beyond it, so the easiest thing to do is fair it in with a blister.

I see. I tried to look up the original prototypes of these planes to see if they had those lumps, but I realised that they might be there even if not for additional modifications. For example if you want to fit something into a wing and the wing isn't thick enough, then I assume you'd have thicken the entire wing, or just a small part of it. Which is what these small fairings are doing, am I right? One interesting thing I noticed is that I only saw these little fairings (excluding the jets) on single engine piston planes, never twin engine (piston), at least I don't think.

In the case of the Spitfire, the original .30 Brownings all fit inside the wings, but when the upgrade to 20mm cannon was done, the receiver of the cannon was too fat and projected above the upper skin, and they're not about to redesign the whole thing, hence the blister fairing.  It's safe to say that any time you see a teardrop bump above a skin surface it's a fairing for something underneath that is protruding.

Sometimes it is for something (e.g. an antenna) that needs to protrude, or possibly a vent / ejection port etc. (some guns retain their spent brass, some don't.) Vaguely similar protruberances (particularly underneath the wing) will be air inlets for cooling.  And even the first version of a plane may have a fairing, simply because a design decision was made for the basic aircraft before a specific part was finalised, and it was easier to put a fairing on than to re-draw the entire plane with a larger frame.


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What are these openings on the TBD/TBM Avenger?
I've been looking at some pictures and models of the TBF1 and TBM3 Avengers, a torpedo and dive bomber from WW2. I've noticed in some cases there are these openings/slots towards the leading edge of the wing on the top, and it seems as if they pass through to an opening to either the very leading edge of the wing, or just below it. The strange thing is that I've seen many pictures and have noticed that in most models these openings/slots are absent. I'm pretty sure they're more common on the TBM3 than the TBD1, if at all. I was wondering what function these have. I have seen one 3D computer model that shows it's just essentially a rectangularly shaped hole going through the entire wing, though I'm not sure if the modeler just guessed at this. Any ideas of what this might be? You might need to zoom in to see them better.

It's a leading edge slot used to improve low speed handling.
Excerpt from Wikipedia:

Partial-span slots are usually found only on the outboard portion of
  the wing where they ensure airflow over that portion of the wing will
  remain unstalled at higher angles of attack than the inboard portions
  of the wing. This ensures the wing root stalls first and contributes
  to docile stall behaviour and maintaining aileron control throughout
  the stall.

You'll notice that the slot is directly in front of the ailerons. Since the TBMs landed on aircraft carriers very close to a stall, the slot ensured adequate roll control during approach and landing.


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Why is the UAE the only country with two flag carrier airlines?
The United Arab Emirates has two flag carrier airlines, Etihad Airways and Emirates. There are 195 countries in the world, and 147 of them have one single flag carrier airline. United Arab Emirates is the only one with two. Is it just a chance occurrence?
flag carrier airways

If you include "hong kong" and "macau" as part of china then they have three entries in that list.

Because the United Arab Emirates is, as the name suggests, a federation of seven loosely-affiliated emirates (the largest and most populous of which are Abu Dhabi and Dubai, in that order), each with its own royal family.  Emirates is based in Dubai; the Emir of Abu Dhabi, Sheikh Khalifa (who also happens, by longstanding convention, to be the president of the UAE), wanted his emirate to have its own flag carrier, and so Etihad came into being (founded by Sheikh Khalifa's personal pilot, no less).


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Does empennage height above the main wing matter
Am still in my preliminary design, am already wondering as to how high above the wing should the empennage (tip of vertical stab) be?

What exactly are you designing? Could you provide some more details?

If you are looking to get the control surfaces out of the wake, you should concern yourself with the horizontal stabilizer more than with the vertical one. Also, more info on what it is you're designing would be helpful.

The critical aspect for Vertical stab height is its rolling torque and how it affects the balance of total side slip forces on the aircraft, including wing, fuselage, landing gear, engine mounts.
As viewed from the side, for the same area, a higher aspect Vertical stab will create more rolling torque and be structurally weaker than a more square design.
More important is Vertical stab area, your weather vane, which affects directional stability and spiral stability.  Very important to get this right.  Adequate area is needed to avoid "Dutch Rolling".  Note that a high wing design needs less dihedral, there for can have a smaller Vertical stab.
Also, the tractor propulsion design, with the CG (and wing)  set as far forward as possible, also lowers the Vertical stab and Horizontal stab area requirement, resulting in significant reduction of drag.
But, unless extreme performance is needed, it is best to slightly overdesign the empennage and play it safe.  Study of existing designs past and present will be of great help.


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Airbus a380 fuel system
Does the aibus a380 has center tank compare with a320,in this picture above,it shows that it has 11 tanks including the wings and the elevator while many aircraftshas together with the center tank (i mean that :eg the a320 ,the fuel are in the wings and cantre tank which is in the centre of the aircraft

Welcome to aviation.SE! I don't understand what you're asking, can you include a link to the picture that you mentioned? That would probably help to make your question clearer. And the [tour] may be helpful if you're new to the site.

This post from Capt. Dave might answer your question: https://www.google.com/amp/s/captaindave.aero/2017/09/07/the-a380-fuel-system/amp/


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who owns the abbreviated name of an airport
is the name of an airport such as LAX the act of the FAA or the ICAO?  from reading, it looks as though the process starts at the ICAO as a recommendation, then is adopted by the FAA?

How it gets assigned and who, for trademark rights and etc, owns it, are probably very different things. The former question, about ICAO & the FAA, is on-topic here; anything about trademark rights & other "ownership" questions, isn't.  Please rephrase your question to be more specific about what you are asking.

I have always heard the 4 letter codes referred to as "ICAO Identifiers".  Obviously the FAA has an interest in mirroring this standard.  Not sure what you mean by who "owns" them, or what that might even entail...

i was looking to have some tshirts printed for my airport workers and wanted to tastefully incorporate the airport code in the design.  being savvy in tm and copyright, im looking to make sure the naming is a federal process.  and if so, the name could never be trademarked or copyrighted.

The 3-letter codes are IATA id's. ICAO codes are 4-letter and in the US are all K plus the IATA code (such as KLAX). For international airports that stuff is all done according to the Chicago convention. The copyright implications are probably better for law.se., but I doubt the codes themselves are copyrightable. Airport logos and such would be though.

It is certainly not a private, commercial trademark.  I would feel confident doing what you plan.

On the other hand, specific marketing slogans incorporating the codes  do exist. For example "I [airplane] OAK" for Oakland International  . A large airport may not take well to employees creating their own slogans, as you may inadvertently deny them future use of the slogan in an exclusive manner.

You might want to look at What is the methodology for assigning airport codes? Trademarks are of course not discussed there, but the assignment is.

I suggest going to law.stackexchange.com and posting a new question: "Are there any potential legal issues with printing airport codes on T-shirts?" You need people who know about trademark law, not people who know about aviation; and you need to ask what you actually want to know (are there any potential legal issues) instead of a tangentially related question (who "owns" the codes).

4-letter names are too trivial to be protected by copyright. Trademark protections require 1) specific applications, 2) commercial usage, 3) that the offending use is relatable enough to the original business to dilute the trademark or harm the business.
(Thus, for instance, an "Airbus" car would be a clear a trademark violation, for a model plane called "Airbus A320" some agreement is preferred just to be safe, and for a book titled "Airbus A320" no communication with Airbus is needed, as it does not compete with any Airbus product, nor does such a title on a book imply being one.)
IATA and ICAO codes amount to nothing more than telephone numbers. They cannot be copyrighted, since they represent abstract concepts rather than a creative expression of one, and they aren't trademarked.
More than that is a question for Law.SE.


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Looking for an API that can provide the amount of flights bought from point a to point b on daily basis
I would like to know if any of you could help me finding an API source to gather information on daily bookings/sales from point A to point B, i.e. how many seats were sold landing or finishing a trip in Dallas airport and where was the beginning of the trip (point of departure).
I will truly appreciate any help, data does not need to be real time, a day or two, even a week delay would be fine. I am trying to correlate demand with other multiple variables but need to get the data from the demand side.
Thanks in advance for your comments
Ben

Not sure you can get the data easily.
IATA developed the NDC standard an API for airlines, which might enable you to check flight bookings between two destinations.
Nonetheless, as with any industry wide standard, it is interpreted in many different ways by the companies implementing it. Hence a pain to develop.
The most simple solution would be to use a set of well defined APIs from an airline ticketing company. Amadeus is one of them and I am almost sure they provide these kind of information.
In both cases, you are looking at quite a high upfront cost (in the thousands).

Thank you for the help! I already tried Amadeus and they replied with a negative answer. I will try IATA!

Let me know if you don't find anything, I might know someone who has the answer.


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What is the maximum (unloaded) range of the Beluga XL?
Airbus states that the range of the Beluga XL is 4000 km at maximum payload. Does anyone have a figure (or estimate) for it's maximum range with no payload?

For an estimate, we can use the Brequet range equation:
$range = V\cdot t_f
= \frac{L}{D} \times I_{sp} \times \ln\left(\frac{W_i}{W_f}\right) $
with:

$V$: optimal velocity
$t_f$: flight time
$L$: lift
$D$: drag
$I_{sp}$:  propulsion efficiency
$W_i$: initial weight
$W_f$: final weight

Assuming the lift to drag ratio $\left(\frac{L}{D}\right)$ and the propulsion efficiency will stay constant, the range will depend on the ratio of initial and final weight.
$range = C \times \ln\left(\frac{W_i}{W_f}\right)$
In case the aircraft departs with the maximum payload, the weight is:
$W_i = W_{oe} + W_{payload} + W_{fuel} = W_{mto}$

$W_{oe}$: operating empty weight: 127 500 kgf
$W_{payload}$:  payload weight: 51 000 kgf
$W_{mto}$: maximum take-off weight: 227 000 kgf
$W_{fuel}$: fuel weight =  $W_{mto} - W_{payload}-W_{oe}$ = 48 500 kgf

The final weight at maximum range is then:
$W_f = W_{oe} + W_{payload}$
Filling in the numbers we find:
4000 km = $C \times \ln\left(\frac{\textrm{227 000}}{\textrm{127 500 + 51 000}}\right)$
That means $C \approx \textrm{16 640}$ for the Beluga XL.
If we now remove the payload and take-off with the same amount of fuel, we find:

$W_i$ = 176 000 kgf
$W_f$ = 127 500 kgf
$range \approx \textrm{16 640} \times \ln\left(\frac{\textrm{176 000}}{\textrm{127 500}}\right) \approx 5365$km

But that is just removing the payload without adding fuel. Of course we can now bring more fuel on board without exceeding the maximum take-off weight.
The fuel capacity of the Beluga XL is 73000 kg (source:Aircraft Characteristics
Airport And Maintenance Planning Beluga XL manual). This changes the numbers to:

$W_i$ = 200 500 kgf
$W_f$ = 127 500 kgf
$range \approx \textrm{16 640} \times \ln\left(\frac{\textrm{200 500}}{\textrm{127 500}}\right) \approx 7530$km

So the Beluga can fly approximately 7500 km when empty, enough to cross the Atlantic from Toulouse, even if there is normal headwind.

It can travel 4259 kilometers or 2647 miles loaded, but I am not sure if Airbus would have a need to publicly document the information of the unloaded range - I doubt this information is accessible.

Why dismiss the case of positioning the aircraft empty? If it takes 3 hops to get from A to B loaded, it may take two legs, or maybe only one, to get from B to A empty.


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Can an aircraft operator hire a Commercial Pilot to fly their aircraft under part 91?
Here is the scenario. Joe owns a Cessna 172. Joe hires Tim to fly him in his 172 from A to B. Tim is a Commercial Pilot. Is this legal?
So far, everyone has said yes to this question, but not one person I have asked can cite a regulation or regulations for me.
Here is my chain of Logic:
Part 61.133(a)(1)(i):

(i) Carrying persons or property for compensation or hire, provided
  the person is qualified in accordance with this part and with the
  applicable parts of this chapter that apply to the operation; and

Alright, let's see which part(s) apply to Tim.
Looking at 119.1(a)(1):

(a) This part applies to each person operating or intending to operate
  civil aircraft - (1) As an air carrier or commercial operator, or
  both, in air commerce; or

Now let's see if any of those apply to us. Perhaps "commercial operator".
1.1:

Commercial operator means a person who, for compensation or hire,
  engages in the carriage by aircraft in air commerce of persons or
  property, other than as an air carrier or foreign air carrier or under
  the authority of Part 375 of this title. Where it is doubtful that an
  operation is for “compensation or hire”, the test applied is whether
  the carriage by air is merely incidental to the person's other
  business or is, in itself, a major enterprise for profit.

Okay. This Tim seems to be operating as a Commercial Operator.
Now look at 119.23(b):

(b) Each person who conducts noncommon carriage (except as provided in
  § 91.501(b) of this chapter) or private carriage operations for
  compensation or hire with airplanes having a passenger-seat
  configuration of less than 20 seats, excluding each crewmember seat,
  and a payload capacity of less than 6,000 pounds shall - (2) Conduct
  those operations in accordance with the requirements of part 135 of
  this chapter, except for those requirements applicable only to
  commuter operations; and

Well we want to be under part 91, so let's look at the exception provided as 91.501(b).
91.501(b):

(b) Operations that may be conducted under the rules in this subpart
  instead of those in parts 121, 129, 135, and 137 of this chapter when
  common carriage is not involved, include - (4) Flights conducted by
  the operator of an airplane for his personal transportation, or the
  transportation of his guests when no charge, assessment, or fee is
  made for the transportation;

Number 4 seems to apply! Awesome!
But let's take a look at 91.501(a):

(a) This subpart prescribes operating rules, in addition to those
  prescribed in other subparts of this part, governing the operation of
  large airplanes of U.S. registry, turbojet-powered multiengine civil
  airplanes of U.S. registry, and fractional ownership program aircraft
  of U.S. registry that are operating under subpart K of this part in
  operations not involving common carriage. The operating rules in this
  subpart do not apply to those aircraft when they are required to be
  operated under parts 121, 125, 129, 135, and 137 of this chapter.
  (Section 91.409 prescribes an inspection program for large and for
  turbine-powered (turbojet and turboprop) multiengine airplanes and
  turbine-powered rotorcraft of U.S. registry when they are operated
  under this part or part 129 or 137.)

What is a Large Aircraft.
1.1:

Large aircraft means aircraft of more than 12,500 pounds, maximum
  certificated takeoff weight.

Okay, a Cessna 172 is not a Large Aircraft or turbojet multiengine. And this is not a Fractional Ownership Program since that requires 2 aircraft in the first place.
So, from my understand, Tim cannot fly for Joe since 91.501(a) says this part does not apply, BUT wait. 91.501(b) says it is allowed.
How is this intrepreted? Does 91.501(b) apply only to large aircraft and such on a fractional ownership program? What am I missing?
Everyone I know says it is allowed, but the rules seem to be different. Any help is appreciated.

Fractional ownership aircraft requires two or more owners, not two aircraft.

"Number 4 seems to apply! Awesome!"  No... this entire subpart governs "the operation of large airplanes of U.S. registry, turbojet-powered multiengine civil airplanes of U.S. registry, and fractional ownership program aircraft of U.S. registry..."  Cessna 172 operations are not covered by 91.501.

P.S.  Regulations are by nature restrictive so you will have a tough time finding one that specifically allows what you do what you are asking.  As are doing, look for any prohibitions in the regs.  Generally speaking if you cannot find something specifically prohibited then by default it should be permitted.

"commercial operator" is where your analysis starts going wrong. It isn't air commerce.

Good string here:  https://forums.jetcareers.com/threads/private-carriage.136819/

@RonBeyer 91.1001(b)(5)(ii) and 2 or more airworthy aircraft.

@MichaelHall that is why I said "seems" because later on I proved that it didn't which is where my confusion came from.

@pericynthion I was concerned about that. If that is the case, then what kind of conclusion would you draw and how?

@MichaelHall thank you so much. That cleared it up for me!

You're welcome.  I had a hard time following your chain of logic because later on you referenced 91.501(b), yet that entire subpart is not applicable.

Does this answer your question? Can a commercial pilot fly passengers for hire without an air carrier certificate?

To answer my own question. As pointed out by @MichaelHall and @pericynthion Tom would not fall under "Commercial operator".
Here is the definition for reference:

Commercial operator means a person who, for compensation or hire,
  engages in the carriage by aircraft in air commerce of persons or
  property, other than as an air carrier or foreign air carrier or under
  the authority of Part 375 of this title. Where it is doubtful that an
  operation is for “compensation or hire”, the test applied is whether
  the carriage by air is merely incidental to the person's other
  business or is, in itself, a major enterprise for profit.

Another term which comes in useful here is:

Operational control, with respect to a flight, means the exercise of
  authority over initiating, conducting or terminating a flight.

In this case, Joe would have operational control since it is his aircraft. Since Commercial Operation means "...person who... engages in the carriage by aircraft...", then Joe is the "person" and not the pilot Joe.
Another term within the definition is "air commerce". This means:

Air commerce means interstate, overseas, or foreign air commerce or
  the transportation of mail by aircraft or any operation or navigation
  of aircraft within the limits of any Federal airway or any operation
  or navigation of aircraft which directly affects, or which may
  endanger safety in, interstate, overseas, or foreign air commerce.

Commerce is the activity of buying or selling. If we look at it from that level, the operator (Joe) is not engaging in air Commerce, because when you are operating an aircraft, you're perfectly allowed to pay for the usage of your own plane. So if this is not air commerce, then it falls under Part 91, and Tom is good to go.
However, if Joe were to engage in air commerce such as shipping stuff, but still hire Joe, then this falls under part 119 then 135 operations.
Refer to this legal interpretation: https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/1993/green%20-%20(1993)%20legal%20interpretation.pdf
Based off this interpretation, the aircraft and operator must be separate from the pilot. Also, the operator cannot conduct air commerce flights.

It seems that "Tom" is good to go, but what about poor "Tim" in the OP?  ;)

"However, if Joe were to engage in air commerce such as shipping stuff, but still hire Joe..." Tim? (Or even Tom?) ;-)


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Can jetliner pilots program departures when specific RNAV procedures do not exist?
Can commercial pilots (e.g. 737 and 737 Max) program departures into their on-board GPS navigation system for the first portion of a flight that doesn't have specific RNAV procedures?

You may ask only one specific question, asexplained in the help center. If you have several questions (even related), ask several questions (possibly including linking to other questions).

OK edited it down to one specific problem.

A Boeing 737 uses a Flight Management System (FMS, see this question for details: What's the difference between FMS and FMC?). This FMS takes inputs from multiple navigation sources/sensors, including inertial, radio, and GPS. One part of this system is the CDU (Control and Display Unit, actually there are two installed), which is one of the interfaces to the FMS:

(source, this is from a simulator, real one looks similar)
On the page in the image above, the departure runways and SIDs for EDDK are shown as an example. The pilots can select the departure procedure that was assigned to them by ATC. This assumes the flight is conducted under Instrument Flight Rules (IFR), but since you asked about commercial operations this will almost certainly be the case.
A departure procedure without any specific RNAV waypoints (e.g. fly runway heading, then radar vectors) will still be selectable in the CDU. An item VECTORS will be displayed on the LEGS page between the departure runway and the first enroute waypoint. Once ATC clears you direct to a waypoint, the CDU can be easily updated by moving this waypoint to the top.
It is also possible to manually enter waypoints into the LEGS page if a pilot chooses to do so. The 737 CDU allows creating pseudo waypoints e.g. by giving a reference waypoint, a distance in NM and a course. This way, a more accurate route can be shown on the Navigation Display (ND). However, when getting radar vectors from ATC it is more likely the pilots will fly using HDG SEL (Heading Select) rather than following waypoints programmed into the FMS using LNAV (Lateral Navigation).

I upvoted over mine...

I am not familiar with the 737, but GPS systems commonly in use by general aviation for the last two decades will allow pilots to load a published departure or approach procedure as long as it is in the unit's database.  And if not, as long as the waypoints were in the database you could create it manually.  It doesn't take a big stretch to presume that modern airliners have the same capability.


text:
Can a commercial pilot decide where to make their turn after departure?
If there aren't published vectors to tell a commercial pilot which heading to take as they climb, can they decide where to make their initial turn on their own or would an ATC always involved in where they make the turn?

The takeoff clearance usually tells them what heading to hold and if any turns are to be made (above 400 feet.) Departure will give turns also.

@MikeBrass don't you mean above 500 feet, at least as far as new PBN rules are concerned (for LNAV engagement)?

The short answer is yes, a commercial pilot can make a decision when to turn.
To clarify a few points though, there really isn't such a thing as a "published vector".  If a departure procedure with heading were to be published it would then become a Standard Instrument Departure, or SID.  True, some SIDs will specify radar vectors, but this simple tells pilots that they should expect ATC to assign headings that will vary depending on traffic, not which heading they can expect to actually fly.
Next, "commercial" pilots don't do anything different than private pilots, airline transport pilots, or military pilots.  When and where you turn during departure depends primarily on whether you are operating under IFR or VFR.  Secondarily, decisions on when to turn will be based on terrain, noise abatement, company policy, and lastly personal preference.
So, considering my answer in light of the above, there is a big difference between a 737 operating IFR on a SID, and a commercial pilot in a 172 towing a banner under VFR out of a non-towered airfield.  If you have a specific scenario you are wondering about you might get a better answer if you can narrow down the question.

Thx. I was referring to a U.S. commercial pilot flying a 737 under IFR. For example if there is a SID, does the pilot have the say where the initial turn would be made right after departure (e.g. 2 miles or 4 miles or 5 miles) before they get vectored? For this example lets say there aren't any noise abatement or terrain issues.

If there is a SID, fly the SID.  If you are told to expect vectors, maintain runway or last assigned until given a new heading. Otherwise I am not quite sure what you are asking without an example.  Each SID is different and there really isn’t a blanket answer.  Why would you turn otherwise?  Your are either cleared your own navigation, or driven around by ATC.  There aren’t really any other options...

Thx. If there is published SID and the turns are always made at 3 miles, who can m ake the decision to start turning at 5 miles? Can a 737 pilot do that? Or would the ATC?

If you have been cleared to fly a SID that requires you to turn at 3 miles and you haven’t turned by 5 you are in violation of your clearance!  ATC does not call your turn for you in case that’s where our miscommunication lies.  When cleared for a SID or STAR you are expected to fly the entire published procedure without further guidance from ATC.  That’s why they are standardized and published, to reduce radio chatter.  ATC assigned vectors should be only out of necessity.  Does that clear things up?

It depends. Commercial pilot could be doing a VFR part 91 flight from his own backyard.
I suspect you meant pilot of an airline flight? Yes, in one way or another he will be told which way to turn 99.9 % of the time, in the USA at least. Whether by tower, ODP, or company guidance.

Thx. I did mean airline pilot. I'm not that familiar with ODP, but is it possible for the company or ATC to direct a change from a turn that's normally made at 3 miles to 5 miles, on a published SID? I'm just wondering what the scenario would be in which that could happen?

@FlyGRL - We are also wondering what the scenario would be in which that could happen.  Two possibilities:  ATC initiated - If they need you to extend beyond the point where you would turn for traffic they will take you off the SID and provide vectors.  Pilot requested - if for weather, minor cockpit emergency, or some other reason, the pilot can always request a deviation from the clearance, even if temporary.  (real emergency just squawk and fly...)  However, the company or anyone else cannot simply direct a change to a SID without asking or telling ATC.  Does this answer your question?

Thx. Would this make a difference? The initial part of the route is defined by a compass heading and not satellite-based. There isn't an open departure. There are no emergencies, no changes in weather, no waypoints in the first segment until well after the turn. Most of the turns were made at 3 miles, now at 5 miles. Here's the SID (RNAV) route description: Climbing right turn heading 210, expect vectors to ----, then on track 009 to cross ------ at or above 13000... on (transition) maintain FL230. Expect filed altitude 10 minutes after departure.


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What's the aisle width of long range business jet?
What's the average aisle width for long range business jet such as Gulfstream G500?

Based on this cabin layout of a Gulfstream G500 found on flexjet.com, I measured the aisle width at various places:

The total width is given as 7' 11'' = 241.3cm. The aisle width at the marked positions is then:

63cm (2' 1'')
68cm (2' 3'')
44cm (1' 5'')
51cm (1' 8'')
46cm (1' 6'')
57cm (1' 10'')
50cm (1' 8'')

This would give an average of 54cm (1' 9'') over the measured positions.
Interestingly, the narrowest part (44cm) is less than the FAA minimum for transport category aircraft with more than 10 seats (Is there any limit on how narrow aisles can be?), which would be 20in = 50.8cm.

:-) I tried to use that very same image from flexjet but had difficulties with its transparent background. Lucky you. jetadvisors.com gives slightly different dimensions (7,3 ft cabin and 5,5 ft floor), but I doubt them. Oh, and I just helped you over the 8,000 points mark. Congrats.

@PerlDuck I think the 7.3 ft would be the full cabin from the inside, the scale in the used picture is including the fuselage.